Reflection type blank masks, methods of fabricating the same, and methods of fabricating reflection type photo masks using the same

ABSTRACT

Reflection type blank masks are provided. The blank mask includes a substrate having a recessed pattern with a pretermined depth, a reflection layer substantially on the substrate, an absorption layer substantially on the reflection layer, and a resist layer substantially on the absorption layer, wherein the resist layer has a recessed part that is formed by transference of the profile from the recessed pattern.

CROSS-REFERENCES TO RELATED APPLICATIONS

This is a continuation-in-part application of application Ser. No.13/614,373, filed on Sep. 13, 2012, now allowed.

BACKGROUND

1. Technical Field

Various embodiments of the present disclosure generally relate to photomasks used in fabrication of semiconductor devices, and to reflectiontype blank masks, methods of fabricating the same, and methods offabricating reflection type photo masks using the same.

2. Related Art

As semiconductor devices become more highly integrated, sizes of circuitpatterns constituting the semiconductor devices have been continuouslyreduced. Thus, there may be some limitations in realizing the finepatterns with a photolithography process utilizing ultraviolet (UV)rays. Accordingly, an extreme ultraviolet (EUV) lithography process hasbeen proposed to form the fine patterns of the semiconductor devices.The EUV rays may have relatively short wavelengths. For example, the EUVrays may have a wave length of about 0.2 nanometers to about 100nanometers.

A reflection type mask may be used in the EUV lithography process. Thereflection type mask may include a laminated reflection layer formed ona transparent substrate and absorption layer patterns (e.g., metalpatterns) formed on the laminated reflection layer. The laminatedreflection layer exposed by absorption layer patterns may reflects theEUV rays and the absorption layer patterns may absorbs the EUV rays.Planar images of the absorption layer patterns (or planar images of theexposed portions of the reflection layer) may be transferred on a waferusing a EUV lithography apparatus (e.g., an exposure apparatus) with thereflection type mask. During the EUV lithography process, the EUV raysmay be irradiated on the reflection type mask. The absorption layerpatterns may absorb the EUV rays while the EUV lithography process isperformed. In contrast, the EUV rays irradiated onto the exposedportions of the laminated reflection layer may be reflected toward aresist layer coated on the wafer through a mirror optical system.

There are many issues in the development of the EUV lithography process.For example, the EUV lithography process may be affected by substratedefects of the reflection type masks used in the EUV lithographyprocess. In particular, it may be difficult to fabricate blank maskswithout any defects because the laminated reflection layer of the EUVmask is formed by stacking a plurality of layers, for example, abouteighty layers of molybdenum/silicon. In order to minimize the influenceof the defects in the laminated reflection layer (e.g., phase defects)on the lithography process, the coordinates and sizes of the phasedefects should be accurately recognized. Fiducial marks may be formed inthe blank reflective type mask to increase the accuracy of the phasedefect inspection, and the fiducial marks may be used as referenceposition marks during inspection of the phase defects.

SUMMARY

Various embodiments are directed to reflection type blank masks, methodsof fabricating the same, and methods of fabricating reflection typephoto masks using the same.

According to various embodiments, a reflection type blank mask includesa substrate having a recessed pattern with a pretermined depth, areflection layer substantially on the substrate, an absorption layersubstantially on the reflection layer, and a resist layer substantiallyon the absorption layer, wherein the resist layer has a recessed partthat is formed by transference of the profile from the recessed pattern.

According to various embodiments, a reflection type blank mask includesa substrate having a protruded pattern with a pretermined height, areflection layer substantially on the substrate, an absorption layersubstantially on the reflection layer, and a resist layer substantiallyon the absorption layer, wherein the resist layer has a protruded partthat is formed by transference of the profile from the protrudedpattern.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the disclosure willbecome more apparent in view of the attached drawings and accompanyingdetailed description.

FIG. 1 is a cross sectional view illustrating an example of a reflectiontype blank mask according to an embodiment.

FIGS. 2 to 4 are cross sectional views illustrating an example of amethod of fabricating a reflection type blank mask according to anembodiment.

FIG. 5 is a process flowchart illustrating an example of a method offabricating a reflection type photo mask according to an embodiment.

FIG. 6 is a cross sectional view illustrating an example of a reflectiontype blank mask according to an embodiment.

FIG. 7 is a cross sectional view illustrating an example of a reflectiontype blank mask according to an embodiment.

DETAILED DESCRIPTION

Various embodiments will be described more fully hereinafter withreference to the accompanying drawings. In explanations of the variousembodiments, the same or corresponding elements may be denoted by thesame reference numerals or the same reference designators. To avoidduplicate explanation, descriptions to the same elements as set forth inthe previous embodiment may be omitted or briefly mentioned in eachembodiment.

The figures are provided to allow those having ordinary skill in the artto understand the scope of the embodiments of the disclosure. Thepresent invention may, however, be embodied in different forms andshould not be construed as limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the presentinvention to those skilled in the art.

Meanwhile, it may be understood that when one element, such as a layer,is referred to as being ‘on (or over)’ the other element (for example, asemiconductor substrate), it may directly come in contact with the otherelement, or a third element or elements may be interposed between thetwo elements etc. Furthermore, in the drawings, the size and thicknessof each layer is enlarged, for ease of description and clarity, and thesame reference numerals designate the same elements throughout thedrawings. In this specification, specific terms have been used. Theterms are used to describe the present invention, and are not used toqualify the sense or limit the scope of the present invention.

In this specification, ‘and/or’ represents that one or more ofcomponents arranged before and after ‘and/or’ is included. Furthermore,‘connected/coupled’ represents that one component is directly coupled toanother component or indirectly coupled through another component. Inthis specification, a singular form may include a plural form as long asit is not specifically mentioned in a sentence. Furthermore,‘include/comprise’ or ‘including/comprising’ used in the specificationrepresents that one or more components, steps, operations, and elementsexists or are added. FIG. 1 is a cross sectional view illustrating anexample of a reflection type blank mask according to an embodiment.

Referring to FIG. 1, a reflection type blank mask 100 may include asubstrate 110, and a laminated reflection layer 120 disposedsubstantially on the substrate 110 to reflect extreme ultraviolet (EUV)rays. Additionally, fiducial marks 130 may be disposed substantially onportions of the laminated reflection layer 120, and an absorption layer140 may be disposed substantially on the fiducial marks 130 and thelaminated reflection layer 120. The absorption layer 140 may absorb theEUV rays, and a resist layer 150 may be formed substantially on theabsorption layer 140. A buffer layer may be additionally disposedsubstantially between the laminated reflection layer 120 and theabsorption layer 140 and substantially between the laminated reflectionlayer 120 and the fiducial marks 130. In various embodiments, a cappinglayer may be disposed instead of the buffer layer. In other embodiments,the capping layer may be disposed substantially between the buffer layerand the laminated reflection layer 120.

The substrate 110 may include a material having a relatively lowcoefficient of thermal expansion. For example, the substrate 110 may bea glass substrate.

The laminated reflection layer 120 may include a plurality of thin filmsconstituting a Bragg reflector to improve its reflectivity to the EUVrays used in a EUV lithography apparatus. In an embodiment, thelaminated reflection layer 120 may include a plurality of highrefractive material layers and a plurality of low refractive materiallayers which are alternately stacked. For example, the laminatedreflection layer 120 may include a plurality of molybdenum (Mo) layersand a plurality of silicon (Si) layers which are alternately stacked.That is, the laminated reflection layer 120 may include the plurality ofmolybdenum (Mo) layers and the plurality of silicon (Si) layers disposedsubstantially between the plurality of molybdenum (Mo) layers. Themolybdenum (Mo) layers may have a relatively high refractive index andthe silicon (Si) layers may have a relatively low refractive index.Alternatively, the laminated reflection layer 120 may be formed byrepeatedly stacking a bi-layer of a molybdenum (Mo) layer and aberyllium (Be) layer, a bi-layer of a ruthenium (Ru) layer and a silicon(Si) layer, a bi-layer of a silicon (Si) layer and a niobium (Nb) layer,a bi-layer of a molybdenum carbide (MoC) layer and a silicon (Si) layer,a bi-layer of a molybdenum compound layer and a silicon compound layer,or a triple-layer of a molybdenum (Mo) layer, a molybdenum carbide (MoC)layer and a silicon (Si) layer.

The stack number of the bi-layer or the triple-layer constituting thelaminated reflection layer 120 may be equal to or greater than ‘30’ toobtain a reflectivity of about 50% or greater. Alternatively, the stacknumber of the bi-layer or the triple-layer constituting the laminatedreflection layer 120 may be equal to or greater than ‘35’ to obtain areflectivity of about 60% or greater. For example, the stack number ofthe bi-layer or the triple-layer constituting the laminated reflectionlayer 120 may be within the range of about 40 to about 60 to obtain areflectivity of about 60% or greater. Further, the laminated reflectionlayer 120 may have a total thickness of about 210 nanometers to about300 nanometers, but not limited thereto. For example, the totalthickness of the laminated reflection layer 120 may be determined inconsideration of a wavelength of the EUV rays used in the EUVlithography process.

The fiducial marks 130 may be used as reference marks during inspectionand/or registration of defects of the blank mask 100. Thus, the fiducialmarks 130 may be substantially disposed in an edge of the blank mask,which may not be transferred onto a chip region of a wafer. The fiducialmarks 130 may have a convex shape in the reflection type blank mask 100,as illustrated in FIG. 1. That is, the fiducial marks 130 may be formedby depositing a fiducial mark layer substantially on the laminatedreflection layer 120 and by patterning the fiducial mark layer. Thus,the fiducial mark layer may be formed of a material having an etchselectivity with respect to the laminated reflection layer 120. Invarious embodiments, the fiducial marks 130 may include a chromecontaining layer or a tantalum containing layer. For example, thefiducial marks 130 may include a chrome nitride (CrN) layer or atantalum nitride (TaN) layer and may have a thickness of about 20micrometers to about 100 micrometers.

The absorption layer 140 may include a material that absorbs the EUVrays. In various embodiments, the absorption layer 140 may include acompound layer containing tantalum (Ta), for example, a tantalum nitride(TaN) layer. The material containing tantalum (Ta) may be more readilyetched using a plasma etch process that employs radicals of a fluorinesystem as etching chemical sources, and the radicals of a fluorinesystem may be widely used in fabrication of semiconductor devices. Thus,the tantalum nitride (TaN) layer may be suitable for the absorptionlayer 140. However, the absorption layer 140 may not be limited to thetantalum nitride (TaN) layer. For example, the absorption layer 140 maybe formed of any material having an absorptivity to the EUV rays.

The buffer layer or the capping layer may be used as an etch stop layerin a subsequent etching process for patterning the absorption layer 140.In various embodiments, the buffer layer and/or the capping layer mayinclude a silicon nitride (SiN) layer, a silicon oxynitride (SiON) layeror the like. In various embodiments, the absorption layer 140 may bedirectly formed substantially on the fiducial marks 130 and thelaminated reflection layer 120 without formation of the buffer layer orthe capping layer.

The blank mask 100 may further include a conductive layer 160 disposedsubstantially on a bottom surface of the substrate 110 substantiallyopposite to the laminated reflection layer 120. The conductive layer 160may cause an electrostatic chucking effect when a photo mask formedusing the blank mask 100 is loaded into a lithography apparatus. Invarious embodiments, the conductive layer 160 may include a chrome (Cr)layer or a chrome nitride (CrN) layer.

According to the reflection type blank mask described above, thefiducial marks 130 having a convex or protruding shape may be disposedsubstantially on the laminated reflection layer 120. That is, thefiducial marks 130 may be formed even without etching the substrate 110.Thus, it can substantially prevent the substrate 110 from beingcontaminated and/or damaged during formation of the fiducial marks 130.In addition, even though some residues of the fiducial mark layer mayremain on the laminated reflection layer 120 after formation of thefiducial marks 130, the residues may be more readily removed during anetching process for patterning the absorption layer 140. This is becausethe main etching gas used in formation of the fiducial marks 130 may bethe same as or similar to that used in the etching process forpatterning the absorption layer 140. Moreover, in the event that thefiducial marks are formed by etching the substrate 110, the fiducialmarks may be substantially covered with the laminated reflection layer120. Thus, it may be difficult to repair the fiducial marks. Incontrast, the fiducial marks 130 according to the various embodimentsmay be formed substantially on a top surface of the laminated reflectionlayer 120. Thus, it may be easy to repair the fiducial marks 130 using aredundancy apparatus.

Now, methods of fabricating a reflection type blank mask according tovarious embodiments will be described in detail hereinafter.

FIGS. 2 to 4 are cross sectional views illustrating an example of amethod of fabricating a reflection type blank mask according to anembodiment. In the drawings of FIGS. 2 to 4, the elements indicated bythe same reference numerals or the same reference designators as used inFIG. 1 denote the same elements.

Referring to FIG. 2, a substrate 110 may be provided. The substrate 110may include a material having a relatively low coefficient of thermalexpansion. For example, the substrate 110 may be a glass or quartzsubstrate. A molybdenum (Mo) 121 layer and a silicon (Si) layer 122 maybe alternately and repeatedly stacked substantially on the substrate110, thereby forming a laminated reflection layer 120. The laminatedreflection layer 120 may be formed by alternately and repeatedlystacking the molybdenum (Mo) layer 121 and the silicon (Si) layer 122substantially on the substrate 110 about forty times to about sixtytimes using a sputtering process. That is, the molybdenum (Mo) layer 121and the silicon (Si) layer 122 may be alternately formed using asputtering apparatus in which a molybdenum (Mo) target and a silicon(Si) target are mounted and introducing an argon gas into the sputteringapparatus. While the molybdenum (Mo) layer 121 is formed, the silicon(Si) target may be substantially covered with a shutter to substantiallyprevent the silicon layer 122 from being formed. Similarly, while thesilicon (Si) layer 122 is formed, the molybdenum (Mo) target may besubstantially covered with the shutter to substantially prevent themolybdenum (Mo) layer 121 from being formed. Although not shown in thedrawings, a single layer of a capping layer or a double layer of acapping layer and a buffer layer may be formed substantially on thelaminated reflection layer 120.

As described above, the laminated reflection layer 120 may be formed byalternately stacking a plurality of molybdenum (Mo) layers 121 and aplurality of silicon (Si) layers 122. This may be for increasing thereflectivity of the laminated reflection layer 120 to extremeultraviolet (EUV) rays used in a lithography process. Accordingly, whilethe laminated reflection layer 120 is formed, contaminants and/ordefects may be formed in the laminated reflection layer 120. If thedefects and/or the contaminants are located in reflection regions of thelaminated reflection layer 120, images of the defects may be transferredon a wafer in a subsequent exposure step and may cause the malfunctionof a semiconductor device. Thus, coordinates of the defects and/or thecontaminants should be inspected and detected to find out coordinates orpositions of the defects and/or the contaminants, and the coordinates ofthe defects and/or the contaminants should be stored in a memory unit todraw an effective layout in a subsequent chip design step. In order tofind out the coordinates of the defects and/or the contaminants, areference mark may be required.

Referring to FIG. 3, a fiducial mark layer may be formed substantiallyon the laminated reflection layer 120. The fiducial mark layer may beformed of a material having an etch selectivity with respect to thelaminated reflection layer 120. For example, the fiducial mark layer maybe formed of a chrome nitride (CrN) layer or a tantalum nitride (TaN)layer. The fiducial mark layer may be formed to have a thickness ofabout 20 micrometers to about 100 micrometers. A resist layer may beformed substantially on the fiducial mark layer, and the resist layermay be patterned to form a resist pattern. Subsequently, the fiducialmark layer may be etched using the resist pattern as an etch mask,thereby forming fiducial marks 130 substantially having a protruding orconvex shape. An etching process for forming the fiducial marks 130 maybe performed using a dry etching technique that utilizes a chlorinebased gas as an etch gas. The resist pattern may then be removed.

Referring to FIG. 4, after formation of the fiducial marks 130, aninspection process may be performed to determine whether defects and/orcontaminants exist on or in the laminated reflection layer 120.

The inspection process may include aligning the substrate having thelaminated reflection layer 120 and the fiducial marks 130 with anoptical system, finding out defects formed on and in the laminatedreflection layer 120 using the optical system, and storing coordinatesof the defects in a memory unit. The coordinates of the defects may becalculated using the fiducial marks 130 as reference marks. The step offinding out the defects may include irradiating physical signals (e.g.,optical rays) outputted from the optical system onto the substratehaving the laminated reflection layer 120 and the fiducial marks 130 andanalyzing rays emitted or reflected from the laminated reflection layer120. If the optical rays of the optical system are irradiated onto thedefects, the defects may scatter the optical rays to form dark fields atthe corresponding positions of the defects. Accordingly, the locationsof the dark fields may be regarded as the coordinates of the defects.

After finding out and storing the coordinates of the defects, anabsorption layer 140 may be formed substantially on the fiducial marks130 and the laminated reflection layer 120. The absorption layer 140 maybe substantially formed of a material that absorbs the EUV rays. Invarious embodiments, the absorption layer 140 may be substantiallyformed of a conductive absorption layer containing tantalum. Forexample, the absorption layer 140 may be substantially formed of atantalum nitride (TaN) layer. The material containing tantalum (Ta) maybe more readily etched using a plasma etch process that employs radicalsof a fluorine system as etching chemical sources, and the radicals of afluorine system may be widely used in fabrication of semiconductordevices. Thus, the tantalum nitride (TaN) layer may be suitable for theabsorption layer 140. However, the absorption layer 140 may not belimited to the tantalum nitride (TaN) layer. For example, the absorptionlayer 140 may be formed of any material having an absorptivity to theEUV rays. In various embodiments, the absorption layer 140 may be formedby introducing an argon gas into an ion beam generation apparatus and bydepositing a copper (Cu) layer, an aluminum (Al) layer, a titanium (Ti)layer or a tantalum (Ta) layer with a nitrogen (N) gas or a helium (He)gas.

Finally, a resist layer 150 may be coated or formed substantially on theabsorption layer 140 to complete the reflection type blank mask 100illustrated in FIG. 1.

Methods of fabricating a reflection type photo mask using the reflectiontype blank mask described above will be described hereinafter.

FIG. 5 is a process flowchart illustrating an example of a method offabricating a reflection type photo mask according to an embodiment.Referring to FIGS. 1 and 5, a fabrication method of a reflection typephoto mask may include providing a blank mask (step 200 of FIG. 5) andforming patterns on the blank mask (step 300 of FIG. 5).

Providing the blank mask (step 200) may include preparing a masksubstrate (step 210), forming a reflection layer substantially on themask substrate (step 220), forming fiducial marks substantially on thereflection layer (step 230), inspecting the reflection layer (step 240),and forming an absorption layer and a resist layer substantially on thefiducial marks and the reflection layer (step 250). Prior to formationof the fiducial marks (130 of FIG. 4), a single layer of a capping layeror a double layer of a capping layer and a buffer layer may be formedsubstantially on the reflection layer (120 of FIG. 4). After formationof the fiducial marks 130, an inspection process may be performed tofind out whether the reflection layer 120 include defects or not. In theevent that defects are detected in the reflection layer 120, coordinatesand sizes of the defects may be calculated or measured and defect dataD1 including the coordinates and sizes of the defects may be stored in amemory unit. The fiducial marks 130 may be used as reference marks orreference positions (hereinafter, referred to as reference points)during the inspection process.

Forming the patterns on the blank mask 300 may include patterning theabsorption layer 140 using defect-less data D3 (step 260 of FIG. 5)after generation of the defect-less data D3. The absorption layer 140may be patterned to form absorption layer patterns exposing portions ofthe reflection layer 120. If the defects (in particular, defects havinglarge sizes) are located in the exposed portions of the reflection layer120, images of the defects may be transferred onto a wafer in asubsequent exposure step. Thus, the defect-less data D3 may be generatedto minimize the number of the defects (particularly, large-sizeddefects) which are transferred onto the wafer in a subsequent exposurestep. That is, the defect-less data D3 may minimize the number and sizeof the defects which are located in the exposed portions of thereflection layer 120. The defect-less data D3 may be generated usingphoto mask pattern data D2 corresponding to circuit patterns and thedefect data D1 generated in providing the blank mask (step 200).

More specifically, the photo mask pattern data D2 may includeinformation on the circuit patterns which may be transferred on thewafer, for example, information on positions where the circuit patternsare formed. Accordingly, the photo mask pattern data D2 may includeinformation on the coordinates of the circuit patterns, which may becalculated using a predetermined reference point (e.g., a circuitreference point). The defect data D1 may include information on thecoordinates of the defects, which may be calculated using the fiducialmarks 130 as reference points. The defect-less data D3 may includeinformation on how the coordinates of the defects correspond to thecoordinates of the circuit patterns. That is, the defect-less data D3may minimize the probability that the defects overlap with the circuitpatterns. As a result, optimum layouts having minimum defects can beobtained.

As described above, it may be difficult to form defect-less layers onthe reflection layer or to completely remove the defects. Thus, it maybe important to reduce or minimize the number and the size of thedefects overlapped with the circuit patterns in order to obtain highquality photo masks. According to the various embodiments, the numberand the size of the defects overlapped with the circuit patterns can bereduced or minimized using defectless data obtained by the inspectionprocess. Thus, the throughput and the yield of the photo masks can beimproved to reduce the fabrication cost of the photo masks.

According to the embodiments set forth above, fiducial marks may beformed substantially on a laminated reflection layer without etching amask substrate. Thus, it can prevent defects or contaminants from beingformed in the mask substrate during formation of the fiducial marks.Moreover, even though defects are formed substantially on the laminatedreflection layer during formation of the fiducial marks, the defects onthe laminated reflection layer may be more readily removed in asubsequent etching process for forming absorption layer patterns.

Further, the fiducial marks according to the various embodiments may beformed substantially on a top surface of the laminated reflection layer.Thus, it can be easy to repair the fiducial marks using a redundancyapparatus.

FIG. 6 is a cross sectional view illustrating an example of a reflectiontype blank mask according to an embodiment. Referring to FIG. 6, areflection type blank mask 400 include a first region 410-1 and secondregion 410-2. The first region 410-1 has a transfer patternscorresponding to patterns which may be formed on a wafer. The secondregion 410-2 has not the transfer patterns. The substrate 410 mayinclude a meterial having a relatively low coefficient of thermalexpansion. For example, the substrate 410 may be a glass substrate. Inthe second region 410-2, the substrate 410 has a reccessed pattern 510.The recessed pattern 510 may be a tranch structure to be formed byetching the upper surface of the substrate 410 with a predetermineddepth. In an example, the recessed pattern 510 may have a depth of about310 nm to about 300 nm.

A laminated reflection layer 420 is disposed substantially on thesubstrate 410. In the first region 410-1, the laminated reflection layer420 is disposed on the upper surface of the substrate 410. In the secondregion 420-2, the laminated reflection layer 420 is disposed on theupper surface of the substrate 410 and in the recessed pattern 510. Inthe event that the depth of the recessed pattern 510 is substantiallysame with the thickness of the laminated reflection layer 420, an uppersurface of the laminated reflection layer 420 in the recessed pattern510 may be substantially coplanar with an upper surface of the substrate410. In the event that the depth of the recessed pattern 510 isdifferent from the thickness of the laminated reflection layer 420, theupper surface of the laminated reflection layer 420 in the recessedpattern 510 may be positioned at higher or lower than the upper surfaceof the substrate 410. In any event, there is the height differencebetween the upper surface of the laminated reflection layer 420 in theregion that the recessed pattern 510 is disposed and the upper surfaceof the laminated reflection layer 420 in the region that the recessedpattern 510 is not disposed. A conductive layer 460 may be disposed onthe lower surface of the substrate 410. The conductive layer 460 maycause an electrostatic chucking effect when a photo mask formed usingthe blank mask 400 is loaded into a lithography apparatus. In variousembodiments, the conductive layer 460 may include a chrome (Cr) layer ora chrome nitride (CrN) layer.

The laminated reflection layer 420 may include a plurality of thin filmsconstituting a Bragg reflector to improve its reflectivity to the EUVrays used in a EUV lithography apparatus. In an embodiment, thelaminated reflection layer 420 may have a multi-layered structureincluding a first reflection layer 421 and a second reflection layer 422which are alternately and repeatedly stacked, and the first reflectionlayer 421 and the second reflection layer 422 may have differentrefractive index from each other. The first and second reflection layers421 and 422 may be alternately stacked at least twice to constitute thelaminated reflection layer 420. For example, the laminated reflectionlayer 420 may include a plurality of molybdenum (Mo) layers and aplurality of silicon (Si) layers which are alternately stacked. That is,the laminated reflection layer 420 may include the plurality ofmolybdenum (Mo) layers and the plurality of silicon (Si) layers disposedsubstantially between the plurality of molybdenum (Mo) layers. Themolybdenum (Mo) layers may have a relatively high refractive index andthe silicon (Si) layers may have a relatively low refractive index.Alternatively, the laminated reflection layer 420 may be formed byrepeatedly stacking a bi-layer of a molybdenum (Mo) layer and aberyllium (Be) layer, a bi-layer of a ruthenium (Ru) layer and a silicon(Si) layer, a bi-layer of a silicon (Si) layer and a niobium (Nb) layer,a bi-layer of a molybdenum carbide (MoC) layer and a silicon (Si) layer,a bi-layer of a molybdenum compound layer and a silicon compound layer,or a triple-layer of a molybdenum (Mo) layer, a molybdenum carbide (MoC)layer and a silicon (Si) layer.

The stack number of the bi-layer or the triple-layer constituting thelaminated reflection layer 420 may be equal to or greater than ‘30’ toobtain a reflectivity of about 50% or greater. Alternatively, the stacknumber of the bi-layer or the triple-layer constituting the laminatedreflection layer 420 may be equal to or greater than ‘35’ to obtain areflectivity of about 60% or greater. For example, the stack number ofthe bi-layer or the triple-layer constituting the laminated reflectionlayer 420 may be within the range of about 40 to about 60 to obtain areflectivity of about 60% or greater. Further, the laminated reflectionlayer 420 may have a total thickness of about 210 nanometers to about300 nanometers.

The absorption layer 440 may be disposed over the laminated reflectionlayer 420. In the area that the recessed pattern 510 is disposed, theabsorption layer 440 is disposed on the laminated reflection layer 420that is filled into the recessed pattern 510. In such a case, the uppersurface of the absorption layer 440 is positioned lower than the uppersurface of the absorption layer 440 in the area that the recessedpattern 510 is not disposed. The absorption layer 440 may include amaterial that absorbs the EUV rays. In various embodiments, theabsorption layer 440 may include a compound layer containing tantalum(Ta), for example, a tantalum nitride (TaN) layer. The materialcontaining tantalum (Ta) may be more readily etched using a plasma etchprocess that employs radicals of a fluorine system as etching chemicalsources, and the radicals of a fluorine system may be widely used infabrication of semiconductor devices. Thus, the tantalum nitride (TaN)layer may be suitable for the absorption layer 440. However, theabsorption layer 440 may not be limited to the tantalum nitride (TaN)layer. For example, the absorption layer 440 may be formed of anymaterial having an absorptivity to the EUV rays.

The resist layer 450 may be disposed substantially on the absorptionlayer 440. In the area that the recessed pattern 510 is disposed, theresist layer 450 has the recessed part 520. The recessed part 520 isformed by transference of the profile from the recessed pattern 510. Therecessed part 520 may be used as reference marks when coordinates ofdefects in and on the laminated reflection layer 420 are calculated.

FIG. 7 is a cross sectional view illustrating an example of a reflectiontype blank mask according to an embodiment. Referring to FIG. 7, areflection type blank mask 600 include a first region 610-1 and secondregion 610-2. The first region 610-1 has a transfer patternscorresponding to patterns which may be formed on a wafer. The secondregion 610-2 has not a transfer patterns. The substrate 610 may includea meterial having a relatively low coefficient of thermal expansion. Forexample, the substrate 610 may be a glass substrate. In the secondregion 610-2, the substrate 610 has a protruded pattern 710. Theprotruded pattern 710 may be a protruding structure to be formed bydepositing a material layer on the upper surface of the substrate 610with a predetermined height. In an example, the protruded pattern 710may have a heigh of about 310 nm to about 300 nm.

A laminated reflection layer 620 is disposed substantially on thesubstrate 610 and the protruded pattern 710. In the first region 610-1,the laminated reflection layer 620 is disposed on the upper surface ofthe substrate 610. In the second region 620-2, the laminated reflectionlayer 620 is disposed on the upper surface of the substrate 610 and onthe upper surface of the protruded pattern 710. In the event that theheight of the protruded pattern 710 is substantially same with thethickness of the laminated reflection layer 620, an upper surface of thelaminated reflection layer 620 on the substrate 610 may be substantiallycoplanar with an upper surface of the protruded pattern 710. In theevent that the height of the protruded pattern 710 is different from thethickness of the laminated reflection layer 620, the upper surface ofthe laminated reflection layer 620 on the substrate 610 may bepositioned at higher or lower than the upper surface of the protrudedpattern 710. In any event, there is the height difference between theupper surface of the laminated reflection layer 620 in the region thatthe protruded pattern 710 is disposed and the upper surface of thelaminated reflection layer 620 in the region that the protruded pattern710 is not disposed. A conductive layer 660 may be disposed on the lowersurface of the substrate 610. The conductive layer 660 may cause anelectrostatic chucking effect when a photo mask formed using the blankmask 600 is loaded into a lithography apparatus. In various embodiments,the conductive layer 660 may include a chrome (Cr) layer or a chromenitride (CrN) layer.

The laminated reflection layer 620 may include a plurality of thin filmsconstituting a Bragg reflector to improve its reflectivity to the EUVrays used in a EUV lithography apparatus. In an embodiment, thelaminated reflection layer 620 may have a multi-layered structureincluding a first reflection layer 621 and a second reflection layer 622which are alternately and repeatedly stacked, and the first reflectionlayer 621 and the second reflection layer 622 may have differentrefractive index from each other. The first and second reflection layers621 and 622 may be alternately stacked at least twice to constitute thelaminated reflection layer 620. For example, the laminated reflectionlayer 620 may include a plurality of molybdenum (Mo) layers and aplurality of silicon (Si) layers which are alternately stacked. That is,the laminated reflection layer 620 may include the plurality ofmolybdenum (Mo) layers and the plurality of silicon (Si) layers disposedsubstantially between the plurality of molybdenum (Mo) layers. Themolybdenum (Mo) layers may have a relatively high refractive index andthe silicon (Si) layers may have a relatively low refractive index.Alternatively, the laminated reflection layer 620 may be formed byrepeatedly stacking a bi-layer of a molybdenum (Mo) layer and aberyllium (Be) layer, a bi-layer of a ruthenium (Ru) layer and a silicon(Si) layer, a bi-layer of a silicon (Si) layer and a niobium (Nb) layer,a bi-layer of a molybdenum carbide (MoC) layer and a silicon (Si) layer,a bi-layer of a molybdenum compound layer and a silicon compound layer,or a triple-layer of a molybdenum (Mo) layer, a molybdenum carbide (MoC)layer and a silicon (Si) layer.

The stack number of the bi-layer or the triple-layer constituting thelaminated reflection layer 620 may be equal to or greater than ‘30’ toobtain a reflectivity of about 50% or greater. Alternatively, the stacknumber of the bi-layer or the triple-layer constituting the laminatedreflection layer 620 may be equal to or greater than ‘35’ to obtain areflectivity of about 60% or greater. For example, the stack number ofthe bi-layer or the triple-layer constituting the laminated reflectionlayer 620 may be within the range of about 40 to about 60 to obtain areflectivity of about 60% or greater. Further, the laminated reflectionlayer 620 may have a total thickness of about 210 nanometers to about300 nanometers.

The absorption layer 640 may be disposed over the laminated reflectionlayer 620. In the area that the protruded pattern 70 is disposed, theabsorption layer 640 is disposed on the laminated reflection layer 620that is disposed on the protruded pattern 710.

In such a case, the upper surface of the absorption layer 640 ispositioned higher than the upper surface of the absorption layer 640 inthe area that the protruded pattern 710 is not disposed. The absorptionlayer 640 may include a material that absorbs the EUV rays. In variousembodiments, the absorption layer 640 may include a compound layercontaining tantalum (Ta), for example, a tantalum nitride (TaN) layer.The material containing tantalum (Ta) may be more readily etched using aplasma etch process that employs radicals of a fluorine system asetching chemical sources, and the radicals of a fluorine system may bewidely used in fabrication of semiconductor devices. Thus, the tantalumnitride (TaN) layer may be suitable for the absorption layer 640.However, the absorption layer 640 may not be limited to the tantalumnitride (TaN) layer. For example, the absorption layer 640 may be formedof any material having an absorptivity to the EUV rays.

The resist layer 650 may be disposed substantially on the absorptionlayer 640. In the area that the protruded pattern 710 is disposed, theresist layer 650 has the protruding part 720. The protruding part 720 isformed by transference of the profile from the protruded pattern 710.The protruding part 720 may be used as reference marks when coordinatesof defects in and on the laminated reflection layer 620 are calculated.

The various embodiments of the inventive concept have been disclosedabove for illustrative purposes. Those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventiveconcept as disclosed in the accompanying claims.

What is claimed is:
 1. A reflection type blank mask, the blank maskcomprising: a substrate having a recessed pattern with a pretermineddepth; a reflection layer substantially on the substrate; an absorptionlayer substantially on the reflection layer; and a resist layersubstantially on the absorption layer, wherein the resist layer has arecessed part that is formed by transference of the profile from therecessed pattern.
 2. The blank mask of claim 1, wherein the recessedpattern is disposed in area in which transfer pattern is not disposed.3. The blank mask of claim 1, wherein the reflection layer includes aplurality of high refractive material layers and a plurality of lowrefractive material layers which are alternately stacked.
 4. The blankmask of claim 1, wherein the recessed part functions as a reference markwhen coordinates of defects in and on the reflection layer arecalculated.
 5. A reflection type blank mask, the blank mask comprising:a substrate having a protruded pattern with a pretermined height; areflection layer substantially on the substrate; an absorption layersubstantially on the reflection layer; and a resist layer substantiallyon the absorption layer, wherein the resist layer has a protruded partthat is formed by transference of the profile from the protrudedpattern.
 6. The blank mask of claim 5, wherein the protruded pattern isdisposed in area in which transfer pattern is not disposed.
 7. The blankmask of claim 5, wherein the reflection layer includes a plurality ofhigh refractive material layers and a plurality of low refractivematerial layers which are alternately stacked.
 8. The blank mask ofclaim 1, wherein the protruded part functions as a reference mark whencoordinates of defects in and on the reflection layer are calculated.